Aspirin Benefit in Colon Cancer and HLA I Antigen

(HealthDay News) — Aspirin use after colon cancer diagnosis improves survival if tumors express human leukocyte antigen (HLA) class I antigen, according to a study published online March 31 in JAMA Internal Medicine.

Marlies S. Reimers, MD, from Leiden University Medical Center in the Netherlands, and colleagues modeled survival in a cohort study with tumor blocks from 999 patients with colon cancer, surgically resected between 2002–2008. HLA class I antigen and prostaglandin endoperoxide synthase 2 (PTGS2) expression were analyzed, and mutation analysis of PIK3CA was conducted. A prescription database was used to obtain data on aspirin use after diagnosis.

The researchers found that the adjusted rate ratio for the overall survival benefit associated with aspirin use after colon cancer diagnosis was 0.53 (P<0.001) when tumors expressed HLA class I antigen and 1.03 (P=0.91) when HLA antigen was lost. A similar benefit of aspirin was seen for tumors with strong and weak PTGS2 expression (rate ratios, 0.68 and 0.59, respectively) and for wild-type PIK3CA tumors (rate ratio, 0.55). There was no correlation noted for mutated PIK3CAtumors (rate ratio, 0.73; P=0.44).

"Aspirin use after colon cancer diagnosis was associated with improved survival if tumors expressed HLA class I antigen," the authors write. "HLA class I antigen might serve as a predictive biomarker for adjuvant aspirin therapy in colon cancer."